When should I us "me" and when should I say "myself" in the sentences below? Thank you!As per me and Ms. Portnoy’s conversation, I am also requesting

As a native English speaker I would avoid either option at the star of this sentence. I would write:

As per my conversation with Ms. Port,
OR
As per Ms. Port's conversation with me,

I am also requesting [I would add here: copies of] all email correspondence between me and Ms. Brad (including emails sent by me).

There’s very little need to use “myself” in this sort of sentence. “My” is almost always correct, “myself” is used for emphasis or an attempt to sound scholarly.

My suggestion:
As per my conversation with Ms. Port’s, I am also requesting all email correspondence between myself and Ms. Brad (including emails sent by me).

I was always taught you cannot put ´between me and ms port’ as it would have to be changed to Ms Port and I

Theres different ways you could write it, but here's one: As per mine and Ms. Port's conversation, I am also requesting all email correspondences between me (or myself) and Ms. Brad (including emails sent by me.)

I'd change it to

As per my conversation with Ms. Port, I am also requesting all email correspondence between myself and Ms. Brad (including emails sent by me).

As per Ms. Port’s and my conversation, I also request all email correspondence between Ms. Brad and me (including emails sent by me).